It has been nowadays desired to reduce emission of greenhouse gases such as carbon dioxide to prevent global warming. Techniques are being developed for recovering carbon dioxide in an exhaust gas from a boiler body so as to dispose the same in the ground or in an ocean.
Thus, an oxyfuel combustion boiler system has been proposed which is suitable for recovery of carbon dioxide in exhaust gas from an oxyfuel combustion boiler and disposal of the same in the ground or in an ocean (Patent Literature 1). In the oxyfuel combustion boiler system disclosed in Patent Literature 1, exhaust gas is drawn at a position downstream of an exhaust gas treatment equipment and upstream of a carbon dioxide separation equipment through an exhaust gas recirculation line. The drawn exhaust gas is fed by a recirculation fan (forced draft fan) to burners of the boiler and through a coal pulverizing mill to the burners.